In a conventional mail sorter machine, mail, which can be of various heights and sizes, are all loaded into the sorter bottom edge justified to support bar code scanning, bar code printing, address reading, and a number of other functions. The current Pitney Bowes high speed postage meter, the DM Infinity, requires that mail be top edge justified so that the indicia or permit can be printed a fixed distance from the top edge of the envelope.
Some prior art justification and registration mechanisms involve a series of angled rollers that drive the mailpiece against a fixed wall. Above the angled rollers are a series of balls, which provide a normal force to the mailpiece to maintain drive between the drive rollers and the mailpiece. This works relatively well when all the envelopes are all approximately the same size (as in an inserter machine, used for production mail). The wall can be adjusted so that the amount of lateral shift required is minimal.
Unlike an inserter machine that is producing mail to be placed in same sized envelopes, sorters must be capable of handling a wide variety of different sized envelopes. Thus, for the sorter scenario, the media size will range from a 5″ long×3.5″ tall postcard to 11.5″ long×7.25″ tall envelope at ⅜″ thick. The difference in height between the shortest and tallest piece will be 3.75″. To accomplish the full justification shift with the conventional inserter registration device, it would require a 3.5″ tall postcard to travel more than its height before coming in contact with a wall. The long distance that it has to travel provides significant opportunities for the mailpiece to skew.
Another deficiency with the prior art design, for use in a mail sorter machine, is that the balls must have enough force to shift over the heaviest piece, while being light enough to allow the angled rollers to slips when the mailpiece hits a wall on the lightest piece. Due to the large difference between the smallest and largest mailpiece, getting the proper force will be difficult, if not impossible for the total range of mailpiece sizes.
Exemplary prior art registration devices are described in U.S. Pat. Nos. 4,775,143, 6,102,391, 6,715,755, 7,416,183, 7,516,904, and 7,614,551, which are hereby incorporated by reference.